Endotracheal Tube Seal and Suction Performance in a Novel Biorealistic Tracheal Model.

BACKGROUND: Endotracheal tube (ETT) cuffs create a seal to protect against secretion entry to the lungs. Cuff inflation currently is recommended at 20-30 cm H2O pressure. ETT designs have variable seal performance in bench studies using rigid tracheal models lacking the dynamic characteristics of the human trachea. We compared ETT designs within a new, biorealistic tracheal model to assess cuff and suction performance in the setting of a compliant trachea. METHODS: Three ETT designs (Mallinckrodt Hi-Lo, KimVent Microcuff, and Sheridan/HVT) were tested for performance by simulant leakage below the cuff and air leakage (measured as return tidal volume ≥ 80% delivered) over a range of cuff (5-25 cm H2O) and end-expiratory pressure (PEEP 0-15 cm H2O). Subglottic suction channel performance was tested in 2 ETTs (TaperGuard Evac [Covidien] and ISIS HVT [Teleflex]) as time to evacuate the simulant. RESULTS: All ETT cuffs provided effective seals at an inflation pressure of 12 cm H2O when PEEP was ≤ 5 cm H2O. The Microcuff ETT sealed at the lowest pressure of 6 cm H2O, whereas the Sheridan/HVT cuff sealed at 12 cm H2O (P = .01). With a PEEP of 15 cm H2O, a reciprocal increase in air leak occurred, requiring a cuff inflation up to 22 cm H2O to maintain a return tidal volume at ≥ 80% delivered. Suction channel performance improved in the lateral position compared with supine for both ETT designs during continuous 15 mm Hg suction pressure (P = .001). CONCLUSIONS: Within a novel model with normal trachea compliance, we found all ETT designs tested to seal at lower than current recommended cuff pressures.

Pediatric convective hemofiltration: Normocarb replacement fluid and citrate anticoagulation.

BACKGROUND: Continuous venovenous hemofiltration (CVVH) may be preferable over continuous venovenous hemodialysis (CVVHD) in sepsis; however, CVVH use is limited by the lack of commercially produced bicarbonate replacement solutions in the United States. Anticoagulation used for hemofiltration traditionally has been either heparin or citrate based, but to date, citrate protocols have been used predominately in CVVHD. When CVVH has been used with citrate anticoagulation, replacement solutions have had to be custom made in the pharmacy. METHODS: We describe a protocol used in a series of 9 children with sepsis who underwent CVVH with the use of a commercially available bicarbonate solution (Normocarb; Dialysis Solutions Inc, Richmond Hill, Ontario, Canada) and a commercially available citrate solution (Anticoagulant Citrate Dextrose Solution Formula A [ACD-A]; Baxter Health Care, Deerfield, IL). This simplified approach to citrate anticoagulation with CVVH used Normocarb as a prefilter replacement solution under provisions of the 1997 Food and Drug Administration Modernization Act. RESULTS: All patients had acceptable levels of solute and ultrafiltration clearance with this approach. CVVH circuit life averaged 71 hours (range, 37 to 131 hours), influenced in part by the industry recommendation to change the circuit at 72 hours, whereas no complications from this protocol were identified. CONCLUSION: Similar to CVVHD, this protocol is effective and simple in its components, using industry-produced solutions, avoiding the need for pharmacy-made solutions, and limiting cost and potential risk for compounding errors. Although not the purpose of this report, the patient survival rate was 55%.

Renal failure and renal replacement therapy.

Continuous renal replacement therapy is an effective means for fluid and solute management in ARF/MOSF. Prospective studies have examined issues of anticoagulation, the impact of replacement/dialysis, the effects of bicarbonate-versus lactate-based solutions, and nutritional and medication clearance. Speculation and bias exists concerning when and for what indications CRRT should be initiated. Many clinicians, supported by data from Ronco and Goldstein, would contest that early institution is better if the risks (eg, access, anticoagulation) are minimal and the possible benefits are maximal. The authors, examining the issues as an intensivist and as a nephrologist, believe that early institution, aggressive replacement/dialysis, and use of citrate-based replacement fluids provide substantive advantages. With the advent of Ronco's recent data on sepsis managed with filtration and plasma absorption, the indication for use of CRRT in MOSF may become more evident regardless of the presence or absence of ARF.

Survival and renal function in pediatric patients following extracorporeal life support with hemofiltration.

OBJECTIVE: To determine variables associated with survival in pediatric patients treated with hemofiltration while receiving extracorporeal life support and to determine the probability for recovery of renal function among survivors. DESIGN: Retrospective database analysis. SETTING: University of Michigan pediatric nephrology database. PATIENTS: All pediatric patients treated with continuous hemofiltration while on extracorporeal life support at the University of Michigan between January 1990 and May 1999. A pediatric patient was defined as any child between birth and 18 yrs of age, including children treated in both the pediatric intensive care unit and neonatal intensive care unit. Indications for extracorporeal life support included both cardiac and pulmonary failure. INTERVENTIONS: Data analysis of patients who were treated with hemofiltration while on extracorporeal life support. Hemofiltration includes both ultrafiltration and hemofiltration with countercurrent dialysis. MEASUREMENTS AND MAIN RESULTS: Thirty-five patients with a mean age of 39 +/- 65 months (median, 3 months) underwent hemofiltration while on extracorporeal life support. Forty-three percent survived to hospital discharge (95% CI, 26%-60%). All deaths occurred in the intensive care unit. Recovery of renal function occurred in 93% of survivors (95% CI, 79%-108%). Mean duration of hemofiltration in survivors, including time during and after extracorporeal life support, was 9 +/- 6 days. All nonsurvivors were on renal replacement therapy at the time of death. In this analysis, decreased survival was significantly associated with the use of vasopressor infusions (p =.01) and the presence of complications (p =.006). Vasopressor infusions were required in 89% of patients, and 37% of patients experienced complications. CONCLUSIONS: In patients receiving hemofiltration while on extracorporeal life support, survival is comparable to that reported in other extracorporeal life support or hemofiltration populations. Decreased survival in these patients may be associated with the use of vasopressor infusions and the occurrence of complications. Recovery of renal function occurs in most survivors.

Pediatric extracorporeal life support after high frequency ventilation: predictors of survival.

Previous studies of extracorporeal life support in pediatric patients have identified variables associated with survival. However, none of these studies focused on extracorporeal life support after failure of high frequency ventilation (HFV). In the present study, we determined variables associated with survival for pediatric respiratory failure patients who received HFV prior to extracorporeal life support, using data reported to the Extracorporeal Life Support Organization Registry from 1992 to 1998. Patients with neonatal diagnoses, immune compromising conditions, or congenital cardiac defects were excluded. The 243 patients who met inclusion criteria had a 58% survival rate (95% CI 48-66%). The mean age was 22 +/- 39 months. Mean duration of mechanical ventilation prior to extracorporeal life support was 6.6 +/- 5.8 days. Venoarterial extracorporeal life support was used in 72% of the patients; venovenous in 28%. The survival rate for the subset of patients with an oxygenation index greater than 42 cm H2O/torr on HFV (n = 122) was not significantly different from the overall sample. We determined that lower mean airway pressure, lower pressure amplitude, decreased oxygenation index, increased PaO2, and increased oxygen saturation on HFV were associated with increased survival in patients who were subsequently treated with extracorporeal life support.

Medication errors and patient complications with continuous renal replacement therapy.

Continuous renal replacement therapy (CRRT) is commonly used for renal support in the intensive care unit. While the risk of medication errors in the intensive care unit has been described, errors related specifically to CRRT are unknown. The purpose of this study is to characterize medication errors related to CRRT and compare medication errors that occur with manually compounded solutions versus commercially available solutions. We surveyed three separate internet-based, pediatric list serves that are commonly used for communications for programs utilizing CRRT. Data regarding CRRT practices and medication errors were recorded. Medication errors were graded for degree of severity and compared between programs using manually compounded dialysis solutions versus commercially available dialysis solutions. In a survey with 31 program responses, 18 reported medication errors. Two of the 18 were related to heparin compounding, while 16/18 were due to solution compounding errors. Half of the medication errors were classified as causing harm, two of which were fatal. All medication errors were reported by programs that manually compounded their dialysis solutions. Medication errors related to CRRT are associated with a high degree of severity, including death. Industry-based, commercially available solutions can decrease the occurrence of medication errors due to CRRT.

Renal replacement therapy in the treatment of confirmed or suspected inborn errors of metabolism.

OBJECTIVE: Analysis of mortality and risk factors for mortality in the use of renal replacement therapy to correct metabolic disturbances associated with confirmed or suspected inborn errors of metabolism. STUDY DESIGN: A retrospective review of an institutional review board-approved pediatric acute renal failure data base at the University of Michigan. Eighteen patients underwent 21 renal replacement therapy treatments for metabolic disturbances caused by urea cycle defects (n = 14), organic acidemias (n = 5), idiopathic hyperammonemia (n = 1), and Reye syndrome (n = 1). RESULTS: There were 14 boys (74%) and 4 girls (26%), with a mean age and weight of 56.2 +/- 71.0 months and 18.5 +/- 19.2 kg, respectively, at the initiation of renal replacement therapy. Overall treatment mortality rate was 57.2% (12 of 21 treatments), with 11 of the 18 patients (61.1%) dying before hospital discharge. Two-year follow-up on those patients demonstrated that 5 patients (71.4%) remained alive. Initial therapy with hemodialysis was associated with improved survival. Ten treatments (47.6%) required transition to another form of renal replacement therapy to maintain ongoing metabolic control, with a mean duration of 6.1 +/- 9.8 days. Time to renal replacement therapy >24 hours was associated with an increased risk of mortality, whereas a blood pressure >5th percentile for age at the initiation of therapy and the use of anticoagulation were associated with a decreased risk of mortality. CONCLUSIONS: Renal replacement therapy can correct the metabolic disturbances that accompany suspected or confirmed inborn errors of metabolism. Our experience demonstrates an approximately 60% mortality rate associated with renal replacement treatment, with more than 70% of survivors living longer than 2 years.

Pediatric hemofiltration: Normocarb dialysate solution with citrate anticoagulation.

Fourteen children, newborn to 17 years of age, underwent continuous veno-venous hemofiltration with dialysis (CVVHD), using a new FDA-approved bicarbonate-based calcium-free dialysis solution (Normocarb) in combination with citrate anticoagulation. Dialysis prescription included use of the PRISMA system (Gambro, Lakewood, Colo., USA), with ACD-A (Baxter, Deerfield, Ill., USA) for anticoagulation and Normocarb (Dialysis Solution, Richmond Hills, Ontario, Canada) for dialysate. Diagnosis included 11 children with sepsis and 3 children with tumor lysis syndrome. Mean weight was 31.6+/-4.7 kg (range 3.7-62 kg) and average length of therapy was 11.4+/-3.7 days (range 6 h to 67 days). Length of circuit patency was 71.3+/-7.2 h (range 6 h to 127 h), which was influenced in part by a decision to change circuits at 72 h as per manufacturer's recommendation. No bleeding occurred. This protocol utilizes industry-manufactured CVVHD machinery with both thermic and ultrafiltration control, with an effective anticoagulation protocol, and industry-produced bicarbonate dialysate. The use of industry machinery and solutions allows for consistent industrial quality assurance standards. This potentially may decrease the cost of therapy and minimize the risk of pharmacy errors that can occur with pharmacy-made dialysis solutions.